TBR: Resistors v. Capacitors in a Circuit

[justadream]

---

Members do not see this ad.

TBR Physics Book II page 219 #39



TBR says that when both switches are closed, the initial surge of energy goes exclusively to the capacitor because they are the path of least resistance.





My question: How do you know that the capacitors are the path of least resistance? In other words, how can you compare the resistance of capacitors with resistors? Do capactiors always have less resistance (e.g., a capacitor with capacitance of 9999999999 F would have less resistance than a resistor with .000000000000000000000001 ohms)?

I guess what I'm asking is: Do we assume capacitors don't impede electron flow (have 0 resistance)?

 

[Cawolf]

Right - I think in these ideal circuits you assume that.

 

[NextStepTutor_1]

Yes, @Cawolf is correct. In ideal circuits, and the MCAT loves their ideal scenarios, we assume that the capacitor does not impede electron flow because of its relative lack of impedement when comparing it to resistors. However, this is not always true, as the explanation suggests. Once sufficient charge has been stored on the capacitor plates it will no longer be the path of least resistance, but initially, once a switch is closed, the current will flow towards the uncharged capacitor before flowing through the resistor because of this "path of least resistance" prinicipal.